Many steps in biological methods require mixing of different solutions together, e.g. a cellular sample with an intent of cell lysis. In the laboratory, this mixing typically is performed manually using a vortex mixer on a laboratory benchtop. However, vortex mixing is difficult to implement on a consumable, point-of-care diagnostic device because diffusion is not sufficient for small quantities of fluid, for viscous solutions, and for solutions of differential densities.
An alternative method for mixing different solutions together uses a magnetic stir plate and a magnetic stir bar capable of rotation. However, forceful contact of the stir bar with walls of a mixing container in which the stir bar is contained during rotation can result in damage to the walls of the container or to the stir bar, as well as contamination of the sample.